Filtering device



Aug. 29, 1939. A. E. SQUIRE 2,171,484

EILTERING DEVICE Filed July 1, 1937 I/mf/y 706. 56 (ya/e5 Patented Aug.29, 1939 1 UNITED STATES PATENT OFFICE Application July 1, 1937, SerialNo. 151,538 In Great Britain December 17, 1936 4 Claims.

The present invention relates to improvements in or relating tofiltering means.

One well known form of filtering device consists of a conical member ofsuitable fluid-perme- 5 able material, for example paper, such memberbeing formed by folding a circular piece of the permeable material,about a diametrical line so as to double the material and then foldingthe folded material again about a line at right angles to the firstfolding line so as to obtain four thicknesses or plies of material, theplies then being separated so that a cone is formed of which one halfconsists of a single thickness and the other half consists of threethicknesses. The so formed filter is then inserted in a funnel or othersuitable support.

Various disadvantages are associated with the above mentioned filters.Thus in such devices a large amount of the material employed, i. e., two

of the three thicknesses forming one half of the cone, serve no usefulpurpose and indeed these additional plies introduce objections not onlyon the ground that they render the permeability non-uniform but also onthe ground that they 5 reduce the total permeability of the filter.

One of the objects of the present invention is to provide filteringmeans which are simple and inexpensive to manufacture.

Another object is to provide filtering means 30 having a uniform degreeof permeability over substantially the whole of their operativesurfaces.

Yet another object is to provide a filtering device which can be madefrom a quantity of filter 35 paper or the like smaller than thatpreviously necessary for making a filter of the same capacity.

With the above and other objects in view the present invention residesin filtering means as 40 hereinafter described and as defined in theappended claims.

Filtering means according to the present invention comprise a sheet offiltering material having edge portions brought together in over- 45lapping or abutting relationship to provide a conical structure andsecured together in any suitable manner, for instance by means ofadhesive or by stitching said edge portions together or by crimping,embossing, perforating or otherwise de- 50 forming them.

The present invention also resides in a method of making a filteringdevice which includes the steps of bending or folding a sheet ofsuitable material so that it assumes or can be caused to 55 assume theform of a conical cup and then securing the abutting or overlappingportions of said sheet in any suitable manner, for instance by means ofadhesive, by stitching said parts together, or by crimping, perforating,embossing or otherwise deforming said parts. 5

Preferably the aforesaid abutting or overlapping portions are securedtogether in such relationship that surfaces of the edge portions whichare on the same side of the unfolded sheet of material contact with oneanother. The edge 10 portions so brought together and secured to oneanother are then preferably folded so that they lie against the outersurface of the conical structure, this step being of particularadvantage where the said portions are secured together by 15 stitches orby a crimping or other operation which involves the perforating of thesaid portions since the perforations will become covered by the side ofthe conical structure and be effectively sealed against leakage. Thesaid folding of the edge 20 portions moreover enables the conicalstructure to fit snugly into a filter funnel.

The aforesaid sheet may be of substantially semi-circular shape whichmay if desired have a flange along the length of the diametrical edge,the said edge or the flange where this is provided being doubled onitself and secured in such doubled relation by any suitable operation.

In order that the invention may be well understood I will now describesome embodiments thereof by way of examples and with reference to theaccompanying drawing in which:

Figure 1 shows an unfolded piece of filter paper, Figures 2 and 3 showintermediate stages in the formation of the filtering device,

Figure 4 shows a perspective view of the finished device, and

Figures 5 and 6 show modified modes of securing together the overlappingparts of the device. 1

Referring to Figures 1 to 4 of the drawing, the filter device is madefrom a sheet of filter paper I of semi-circular form with a flange orextension 2 along its diametrical line 3. This sheet is folded about theradial line 4 so that the two halves of the paper are superimposed asshown in Figure 2. The over-lapping parts of the flange or extension 2are then secured together for instance with the aid of a crimping orlike machine forming two rows of depressions 5, 5.

The folded flange or projection 2 is then folded about the line 3 sothat the crimped portion abuts against the body of the filter as shownin Figure 3. If desired the step of folding the flange may beautomatically eifected by an attachment fitted to the crimping machine.

The filter papers can be conveniently stacked in collapsed condition asshown in Figure 3 and can be easily expanded, as shown in Figure 4, foruse when required.

It will be readily appreciated from the form of the sheet I and the modeof folding such sheet that the possibility of any material escaping pastthe apex of the cone or through the over-lapping parts of the materialwithout being filtered is prevented and at the same time the amount ofmaterial employed in the manufacture of the filter is greatly reduced ascompared with'that required for the usual form of filter papers and thepermeability is uniform over substantially the Whole area of the paper;

The above described embodiment of the present invention includes tworows of indentations serving to secure together the overlapping parts ofthe extension 2 and'these rows are located nearer to the edge of saidflange than to the folding line 3. It is to be understood however thatthe particular position of such rows may be varied as also may be thenumber of rows. Thus for example Figure 5 shows a modification in whicha single series of depressions 6 is formed, such depressions howeverbeing preferably a little longer than those shown. in Figures 2 and 3 inorder to ensure the security of the assembled device.

Moreover it is to be understood that the doubled-flange need notnecessarily be secured by a crimping, or embossing operation but may besubjected to any other suitable treatment. Thus for instance in somecases the overlapping portions of the flange may be secured together bymeans of adhesive and in other cases by means of stitches 1 as shown inFigure 6, the preferable mode of securing in some cases being determinedby the nature of the filtering material and the use for which the filteris required.

Whilst I have hereinbefore described some examples of my invention Iwish it to be understood that there may be various other embodimentsfalling within the scope of the appended claims. Thus for example thedevices may be made of any desiredshape and dimensions, any suitablematerial maybe employed from which to form such devices and in somecases the filter may be made from two or more sheets of superimposedmaterial.

I claim:

I. A method of forming a filtering device comprising taking a sheet offilter paper of substantially semicircular shape with a flangeprojecting along its diametrical line, folding said sheet about a radialline perpendicular to said diametrical line so as to form two quadrantsofa circle, securing together the superimposed parts of said projectingflange portion, folding said secured flange portions about saiddiametrical line and then opening said two quadrants to form a conicalstructure.

- 2. A method of forming a filtering device comprising taking a sheet offilter paper of substantially semicircular form with a flange projectingalong its diametrical line, folding said sheet about a radial lineperpendicular to said diametrical line so as to form two superimposedquadrants and flange portions, crimping together the superimposed partsof said flange portion in a row spaced from said diametrical line andfolding said flange portion about said diametrical line back on tofolded sheet whereby to form a device which upon opening out forms aconical structure. r

3. A filter device comprising a sectorially shaped sheet of filter paperhaving flangedike projections extending along the subtending radiithereof, said sheet being folded symmetrically about a'bisecting radiusand the superimposed flange-like projections being secured together andthen folded back upon the body of the sheet j along the radius formed bysaid superimposed subtending radii. 7

l. A filter device comprising a s'ectorially shapedsheet of filter paperhaving flange-like projections extending along the subtending radiithereof, said sheet being folded symmetrically about a bisecting radiusand the superimposed flange-like projections being secured together by acrimped line, said crimped line being spaced outwardly from saidsuperimposed subtending radii and-the flange-like portion being foldedback upon the body of the sheet about said superimposed subtendingradii.

I ALFRED-EUSTACE- SQU'IRE.

